Method of forming brake drums



June 22, 1937. F. H. .LEJEUNE 2,084,814

METHOD OF FORMING BRAKE DRUMS I Filed Jan. 22, 1934 2 Sheets-Sheet l NNNNNN OR ATTORNEYS June 22, 1937;

INVENTOR Q/aoze BY W ATTORNEYS ITE Patented June 22, 1937 STATES PATENT EHQE METHOD OF FORMING BRAKE DRUMS Application January 22, 1934, Serial No; 707,800

9 Claims. '(Cl. 29-1522) The invention relates to the manufacture of hubs and brake drums for vehicle wheels, and has'for its primary object the obtaining of a construction either of the brake drum or of an integral brake drum'and wheel hub which can be formed from a forged blank. It is a further objecti to form the structure of a relatively high carbon'steel which after proper heat treatment H will develop desirable characteristics both in the brake flange and in portions of the hub. With these and other specific objects in view the invention consists in the product and process as hereinafter set forth.

Fig. 1 is a cross section in the plane of the axis through one form of my improved hub and brake drum;

Fig. 2 is a similar view through a construction designed for the driving wheels;

Figs. 3, 4, 5, 6, and 7 illustrate the successive steps in the forming of the structure illustrated in Fig. 1;

Fig. 8 illustrates the forged blank for forming a brake drum without the hub;

Figs. 9 and 10 illustrate the successive steps in the forming of said drum.

In the present state of the art it is usual to form the brake drum separate from other portions of the vehicle wheel. There have, however, been constructions in which the drum is integral with the wheel hub, both parts being formed of cast metal. With my improved construction the drum, either integral with or separate from the hub, is formed from a forged blank which is-subsequently fashioned by spinning to the desired form. As illustrated in Figs. 3 to 7, A is a drop forging formed from a heated billet of suitable size and which as shown has a hub portion B with tapering recesses C and D in opposite ends thereof separated by a web E. Surrounding the hub portion B is a cupped portion F including a disk portion F and an obliquely extending bulbular flange F Such a structure can be readily forged as the tapers are such as to provide the required draft for the forming dies.

The forged blank as shown in Fig. 3 is next pierced to remove the web E and the tapering end of the hub portion B is expanded as shown at B, Fig. 4. The blank is then placed in a spinning machine including a spinning head G recessed to receive and to conform to the convex portion of the blank and a clamping plunger H recessed to receive the hub B and clamping against the portion F. The bulbular portion F of the blank is then spun around the curve G and over the periphery G of the head G, this being preferably accomplished by a spinning roll I having its axis transverse to the spinning axis. The resultant form is a conical flange J which in cross section extends substantially at right angles to,the portion F The blank is then removed from the spinning machine, is reheated and replaced in the machine but adjacent to a head K having an obliquely extending portion K substantially at right angles to the portion F of the blank. The blank is then further spun by means of a roll L which reverses the inclination of the portion F conforming the same to the inclination K and extending the bulbular portion J over the periphery of the head. A sec ond roll M having its axis parallel to the spinning axis is then pressed against the portion J elongating the same over the periphery of the head K and otherwise fashioning it to the desired form, such for instance as with a marginal bead or flange N and a reinforcing rib N. As shown in Fig. 6, the next operation is to re-strike the blank as shown in Fig. 7, the annular die 0 having its straight face 0 parallel to the face of the head K. The blank thus fashioned is next heat treated or normalized to develop the desired physical characteristics in the metal, preferably forming a lamular perlitic structure. The blank is then-trued, preferably by an expanding die which completes the structure as shown in Fig. 1.

The structure shown in Fig. 2 is formed in substantially the same manner as that shown in Fig. 1, but has the additional feature of a cylindrical flange P which forms the race for the roller bearings of the driving wheels. t is usual practice to make such a race member separate from the hub but with my improved construction it may be made integral therewith. However, it may be desirable to develop in this portion a harder character than for the balance of the structure, which may be accomplished by quenching the flange P at a higher temperature than that required for the other portions.

In Figs. 8 to 10 inclusive I have illustrated the method of forming the drum separate from the hub. For this purpose a cupped blank Q is forged, having an annular portion Q containing suflicient metal for developing the drum and a web portion Q A hole is then punched in the web portion and the blank is placed on a spinning machine having a head R corresponding in shape to the forging. The portion Q is then spun around over this head and around the periphery thereof, the subsequent operations being similar to those previously described.

Some of the advantages of this method of forming the drum and hub are First, the material for forming the forged blank can be obtained at lesser cost than sheet material generally used in the forming of the drum;

Second, by limiting the radial dimension of the forged blank it may be fashioned with much less power than would be required for forging the entire drum;

Third, by first inclining the web of the blank.

in the opposite direction from that in the cupped structure the portion for forming the braking flange may be bent at right angles to the web and without enlarging the radius to be greatly in excess of that of the finished drum;

Fourth, by then reversing the inclination of this web portion the portion for forming the braking flange is moved axially over the forming head where it can be further fashioned to the desired form.

As has been stated, the product is formed of a comparatively high carbon steel, preferably a",

manganese steel such as the following:

' Carbon .65 to .75

Manganese .65 to .85 Silicon .15 to .30

This material after heat treatment will devel- 0p in the braking flange physical characteristics far superior to those obtained from any low carbon steel or even those of a cast structure. It is also possible by this method to so distribute the metal as to obtain the required thickness in the braking flange with a comparatively thin web portion so that the weight of the combined unit is less than would be possible if manufactured in any other way.

What I claim as my invention is:

1. In a method of forming brake drums, the steps of forging a conical cupped blank of smaller diameter than the finished drum but with sufficient metal in the walls of the cup for forming the complete drum, and spinning the blank to successively radially enlarge the conical cup, turn a reverse flange from the peripheral portion of said conical cup and in refashioning the conical cup and reverse flange into drum form.

2. In a method of forming an integral wheel hub and brake drum, the steps of forging a blank thereof largely concentrated in the outer portion but containing sufficient metal in the walls thereof for forming a complete drum, spinning said blank to successively radially enlarge said cupped flange, turn a reverse flange from the outer portion thereof, and to refashion into drum form maintaining a concentrated mass of metal in advance of each refashioned portion.

3. In a method of forming an integral wheel hub and brake drum, the steps of forging a blank having an oppositely tapering hub portion with conical recesses in opposite end portions thereof, and with an encircling cupped flange, the latter being of a diameter less than that of the finished drum but with sufiicient metal in the walls thereof to form the complete drum with the mass thereof largely concentrated in the outer portion of said walls, piercing the blank to remove the metal between the opposite conical recesses therein, expanding the small end of the tapering hub, spinning the blank to successively radially enlarge the cupped flange thereof, turn a reverse flange from the outer portion of the cup and refashion into drum form maintaining a concentrated mass of metal in advance of each finished portion.

4. In a method of forming brake drums, the steps of forging a cupped blank of smaller diameter than the finished drum but with sufficient metal in the walls thereof for forming the complete drum with the mass thereof largely concentrated in the outer portion of said walls, hot rolling said blank against a formed head to progressively force the concentrated mass of metal radially outward and to form a reverse flange over the periphery of said head and in refashioning to drum form.

5. In a method of forming brake drums, the steps of forging a cupped blank of smaller diameter than the finished drum but with suificient metal'in the walls thereof for forming the complete drum with the mass thereof largely concentrated in the outer portion of said walls,.

hot rolling said blank against a cup-shaped formed head to progressively force the concentrated mass of metal of the cup radially outward and to bend the same over the periphery of said head to form an obliquely extending flange, and further hot rolling the blank against a second head having a reversely inclining portion and of the form of the drum to refashion into conformity to said form.

6. In a method of forming brake drums, the steps of forging a cupped blank of smaller diameter than the finished drum but with sufficient metal in the walls thereof for forming the complete drum with the mass thereof largely concentrated in the outer portion of said walls, hot rolling said blank against a formed head to progressively force the concentrated mass of metal of the cup radially outward and to bend the same over the periphery of said head, further hot rolling the blank against a second head having the form of the drum to refashion into conformity to said form, and further hot rolling the peripheral portion of the refashioned blank to externally rib the same.

7. In a method of forming brake drums, the steps of forging a cupped blank of smaller diameter than the finished drum but with sufficient metal in the walls of the cup for forming the complete drum with the mass thereof largely concentrated in the outer portion of said Walls, hot rolling the blank against a formed head to radially enlarge the walls of the cup and to turn a reverse flange over the periphery of said formed head, the thickness of metal in said turned flange being greater than that in the walls of the cup and in refashioning said flanged cup into drum form, retaining greater thickness of metal in the flange than in the web portion.

8. In a method of forming brake drums, the steps of forging a conical cupped blank of smaller diameter than the finished drum but with sufficient metal in the walls of the cup for forming the complete drum with the mass thereof largely steps of forging a conical cupped blank of smaller 75 diameter than the finished drum but with sufficient metal in the Walls of the cup for forming the complete drum with the mass thereof largely concentrated in the outer portion of said walls, spinning the blank to successively radially enlarge the conical cup and turn a reverse flange from the peripheral portion thereof, further spinning to refashion said conical portion into a reverse conical portion and the flange portion into an externally ribbed drum flange.

FRANK H. LE JEUNE. 

